Signaling system



APll 4, 1944- V- c. G. MILLER 42,345,825

` SIGNALING SYSTEM Filed July 29, 1942 2 Sheets-Sheet l S TA TION WWW WM A TTORNEV Bfr RELEASE April 4, 1944. C, G, MILLER SIGNALING SYSTEM Filed July 29, 1942 zsn'etsshee't 2 /A/l/.'A/TOR` C. G. M/LLER BLW Y l www* ATTORNEY Patented Apr. 4, 1944 SIGNALING SYSTEBI Charles G. Miller, Montclair, N. J., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 29, 1942, sei-iai No. 452,724

6 Claims.

This invention relates to signaling systems and more particularly to systems for sending out from a central point, such as a telephone central oce, four characteristic alarm signals under control of selective keys located at another point, remote therefrom, in which an answer-back signal of the character sent out from the central point i transmitted back to the lcontrol point. f

A feature of the invention resides in controlling the sending out of the characteristic alarm signals by the simultaneous energization of two different conductor combinations of a group of four conductors extending between the control point and the central point and in transmitting an answer-back signal over one of the remaining two idle conductors when the alarm signal is sent out. Another feature resides in means for giving an alarm responsive to the simultaneous energization of more or less than two of said four conductors.

The invention will be yunderstood from the following description when read in connection with the accompanying drawings Figs. 1 and 2 of which, when placed together, with Fig. 2 at the right of Fig. l, shows `a control or transmitting station to the left of the broken line A-A (Fig. l), a central switching point between the broken lines A-A and X--X and to the right of the broken line X-X a plurality of outlying signal stations.

Referring to the drawings, the equipment at the control station, to the left of the broken line A-A, consists of a set of iive push-button keys of the so-called latch plate type, identied as YK, BK, RK and WK, wherein a depressedkey is automatically locked in its operated or depressed condition until automatically released and restored by the depression of another key of the set. Also located at the control station are alternating current signal devices responsive to telephone ringing current each of which has a characteristically different sound, for example, in the present arrangement one oi these devices is shown as a telephone bell or ringer and the other as a buzzer, i. e., a ringer mechanism not equipped with gongs. These devices will be reierred to later.

Extending from the control station to the central switching point are four conductors identifled as T, R, Tl and Rl which in practice may be two cable pairs. At the central switching point these tour conductors are individually connected to battery in series with an individual relay identified as A, B, C and D, respectively.

At the control station line conductors T, R., Tl and R! are so connected to the switch contacts of keys YK, BK, etc. that operation of any key simultaneously grounds two of the four conductors in different combinations, to operate two of the four relays, A, B, C and D depending on the key operated.

At the central switching point operation of any two of the relays A, B, C or D in dierent combinations, causes operation of other relays to nally cause alternating ringing current to be transmitted over line conductors such as Ll or L2 to a plurality of signal stations such as station l shown to the rightof broken line X--X' on Fig. 2.

A further understanding of the arrangement of the present invention will be gainedfrom the following description. of the operation of the system in which it will be rst assumed that the control station desires to cause the -buzzers l5 at all signal stations, such as station 1, to be periodically sounded at a predetermined rate, as for example, soundingfor four seconds followed by a two second silent interval-and periodically peated, which station signal, i; e., a signa-l of four. second duration followed by a two second silent interval will be hereinaftercalled a yellow* signal.

To transmit the yellow signal the attendant at the control station will depress the key identified as YK, thereby releasing the th or release key to remove ground from the conductors R and RI and release relays C and D. It will be hereinatter understood that the release key and relays C `and D are normally operated and serve to maintain a check on conductors T, Tl, R and R! whereby a trouble alarm will be given at the central switching point in case of a grounded or open condition thereof.

When key YK is fully depressed, ground `will be connected to conductors and R thereby operating relays .fi and the circuit for relay A, including conductor T and lower contacts of relay RW.

The combined operation of relays A and C and the release ci relay D completes a circuit to operate relay YS which can be traced from ground, back contact of relay TA, contact l of relay D, contact'i` of relay C, contact 4 of relay B, Contact 5 of relay A, contact S of relay Y, contact l and lower winding of relay YS to battery. Relay YS operates in this circuit and closes its Contact 8 to complete a locking circuit for itself including its upper winding which can be traced from battery, upper winding of relay YS, contact 8,.c:onductor 9 and contacts of key RLS to ground. Relay YS also closes its contact Ul thereby completlng a circuit to operate relay Y which can be traced from battery, winding of relay Y, contact rIll of relay YS, contact 6 of relay Y, contact 5 of relay A, contact 4 of relay B, contact 2 of relay C and contact I of relay D to ground at the back contact of relay TA. Relay Y in operating locks at its contact II to ground over the operating circuit just traced. Relay Y in operating also closes its Contact I2 thereby completing a circuit to cause relay YB to periodically operate and release in step with interrupter YR which interrupter causes relay R3 to alternately operate for four seconds and release for two seconds thereby connecting ground over contacts I2 of relay Y to relay YB at the same rate. Operation of relay YB closes its multiple contacts I3, I4, etc. thereby controlling the Operation of a plurality of relays such as ACY which in turn connect ringing current to line wires such as LI extending to buzzer signal devices such as I 5 at the signal stations I, 2, etc. Operation of relay YB also closes its contacts I6 thereby connecting ringing currents over wire II to conductor TI, idle at this time, which conductor is connected, at the control station, to a buzzer device I8 before referred to, which operates in synchronism with the buzzer signal at the signal stations as an indication to thel control station attendant that the yellow signal is being sent out from the central switching point.

When relay YS operated, it also closed its contacts I9 and 20 to light the master pilot lamp AR, and lamp Y individual to relay YS, which `lamps serve as an indication at the switching point that an alarm signal is being sent out and that it is a yellow signal.

If, after a predetermined interval of time during which the yellow signal is transmitted, two minutes for example, the control station attendant desires to terminate the signal, he will operate therelease key of the key set thereby releasing key YK and removing ground from relays A and C which thereupon release. Relay A in releasing opens its contact 5 thereby opening the previously traced locking circuit for relay Y which releases thereby stopping the transmission of the alarm. Relay YS, however, which locks up to key RLS, remains operated and lamps Y and AR remain lighted until an attendant at the central switching point manually operates the key RLS. This'is a guard feature to insure the presence of an attendantduring the transmission of an alarm. In practice the attendant at the control switching point upon noting the lighted lamps Y and AR will immediately operate key RLS to open the terval, which will be hereinafter called a Blue,

signal, key BK at the control station will be operated thereby connecting ground to conductors T and RI and unlocking the release key which restores to normal whereupon relay C will release but relay D will remain operated and relay A operates thereby completing a circuit to operate relaylBS, which locks to ground at key RLS and completes a circuit to operate relay BL, which locks to ground at relay TA. Relay BS at its lower contacts lights lamps B and AR. Relay BL closes its contact 2l thereby connecting interrupter IB to relay YB, which alternately operates and releases every half second thereby controlling relay ACY to actuate the buzzers at stations I, 2, etc., at this same rate.

Operation of relay YB closes its contacts I6 thereby connecting ringing current every half second to lead I'I, and conductor TI (now idle), to actuate the buzzer I8 at the control station in step with the buzzers at the signal stations.

As before the attendant at the central switching point upon noting lamps B and AR, actuates the key RLS thereby opening the locking circuit for relay BS which releases.

In a like manner when the attendant at the control station desires to repeatedly operate, the bells at the signal station for four seconds followed by two second silent intervals which signal will be called the Red signal, he will operate the key RK which restores key BK, if operated, and grounds conductors TI and R thereby operating relays B and C at the central switching point and restoring the other relays to normal to successively operate relays RS and R, light lamps R and AR, and connects ground at contacts 22 of relay R3, which relay is controlled by interrupter YR, to relay RW which in turn controls relay ACR to operate the ringers (bells) such as 23 at the signal stations.

Relay RW at its contacts 24, connects ringing current over lead 25 to idle conductor T to which is connected, at the control station, a telephone ringer 26 which responds in step with the ringers such as 23 in the signal station.

In a similar manner operation of key WK at the control station causes ground to be ccnnected to conductors TI and RI to operate relays B and D in combination to successively operate relays WS and W and light lamps W and AR. Relay W, in operating, connects ground at its contacts 27 to steadily Operate relay RW which in turn operates relay ACR to cause the ringers or bells such as 23 at the signal station to operate as long as the key W at the control station is held Operated. This signal is called the white or all-clear signal. Ringer 2S at the control station will operate as long as relay RW is operated.

When the control station desires -to discontinue a signal initiated by the operation of one ci the four keys YK, BK, RK or WK, operation of the release key will restore the previously operated key and, by grounding conductors RI and R, will operate relays C and D'.

With relays C and D operated and relays A and B released, a circuit condition is established to maintain a trouble check on the four conductors T, TI, R and RI as follows: RelayA in its released condition completes a circuit from ground, resistance 28, contacts 29 of relay A and upper windin-g of differentially wound relay TBL to battery. A parallel circuit is also established through this same winding from ground, resistance 30 and contact 3| of relay B, also released. With relays C and D operated, two parallel circuits are completed through the lower winding of relay TBL as follows: ground, resistance 32 and contact 33 of relay C, to the lower winding of relay TBL and from ground, resistance 34 and contact 35 of relay D to this same lower winding. Resistances 28, 3G, 32 and 34 are of equal value as are the two windings of relay TBL and therefore under normal conditions currents of equal value iiow in the relay windings and, due to the connection of the windings, neutralize each other and have no effect on the relay. If, however, a short circuit occurs between T and R or Tl and RI, if either R or Rl should become open, or T or TI should be grounded, the before-described balance will be disturbed and relay TBL will operate which in turn will operate relay TA to light the trouble pilot lamp TBL as an alarm signal.

It will be obvious that in the event no one of said relays is in an operated condition, or a different number than two are operated, i. e., 1, 3 or 4, an unbalanced condition will exist with respect to current flowing in the two windings of relay TBL, thus causing its operation and giving an alarm. It will be noted from the preceding description of the operation of relays YS, etc. that the circuits therefor include a ground connection supplied at the back contacts of relay TA, and consequently in the case just described wherein the trouble relay TBL operates in response to an unbalance in the current iiowing in its two windings due to a non-standard condition of relays A, B, C and D, relay TA will be operated which closes a circuit at its front contact to light the trouble lamp TBL and at the same time disconnects ground at its back contact to prevent operation of any one of the four relays YS, BS, RS or WS.

In case of a trouble condition, operation of key OS will disconnect ground from the upper contacts of relay YB and RW thereby preventing any false relay operation at the switching point from sending out a false alarm.

What is claimed is:

l. In a signaling system, a control station and a switching station, four transmission channels connecting said control and switching stations, means at the control station for selectively and simultaneously `energizing different combinations of two of said four channels, a relay at the switching station individual to each channel and operated by the energization thereof, a signal station comprising two characteristically different alternating current signal devices, translating means selectively controlled by the simultaneous operation of different combinations of said channel relays for selectively operating either of said station signals in either of two different manners and other means controlled by said translating means for transmitting a signal to said control station over an idle one of said channels of the same characteristic as, and simultaneous with, the signal being transmitted to the signal station.

2. A system in accordance with claim 1 characterized in this that means are provided for giving an alarm, said means being responsive to the operation of a different number than two of said channel relays.

3. A system in accordance with claim l characterized in this that means are provided, responsive to the operation of a different number than two of said channel relays, for giving an alarm, and for preventing control of said translating means.

4. In a selective signaling system, a sending station, a translating station, and a signal receiving station, four signaling channels between said sending and translating stations, means at the sending station for selectively and simultaneously energizing different two channel combinations of said four channels, a relay at the translating station individual to each channel and operated by the energization thereof, translating means individual and responsive to each operated combination of said channel relays for causing the transmission of a characteristically different signal to said signal station and means responsive to the transmission of a signal to said signal station to simultaneously transmit a similar signal to said sending station over an idle one of said channels.

5. A system in accordance with claim 1 characterized by means for giving an alarm responsive to any condition of said channel relays other than the simultaneous operation of two to the exclusion of the others.

6. In a signaling system, a control point, a switching station, and a signal station, a pair of characteristically different signal devices at said signal station, switching means at said switching station for selectively operating either one of said station signal devices in a plurality of characteristically diierent manners, a plurality of conductors connecting said control point and switching station, means at the control point for selectively controlling said switching means over different equal-number combinations of said conductors, a pair of signaling device at said control point of similar characteristics to the devices at the signal station and means controlled by said switching means when operating a station signal device for simultaneously operating the corresponding signal device at the control point over an idle one of said plurality of conductors in the same characteristic manner as that of the station device being operated.

CHARLES G. MILLER. 

